Seemed like a good idea at first, but I can quickly think of many shortcomings:

I wouldn't know wtf my password is. And in case a login to one of my sites fails, I wouldn't be able to manually copy paste the password and go step by step?

What if the domain name of the site changed? How is it supposed to work with mobile versions like m.Facebook.com?

Or how would it work with apps? Is there a way to tell a login applies to multiple sites?

I'd be stuck in this stateless non-transparent world without knowing wtf is going on I guess. And not to mention I cannot maintain things like notes/cc info etc.